In-situ measurement of total dose radiation effects on parallel plate MOS capacitors using the NPS linear accelerator

Abstract

The study of radiation effects to electronics circuits has been ongoing almost as long as there have been satellites and spacecraft in space. The response to radiation over the planned life of the space system is of great concern to system designers. Operational amplifiers are one of the most basic elements in all electronic systems. This research examines radiation effects of part of a Metal Oxide Semiconductor (MOS) operational amplifier and is applicable to Complimentary MOS (CMOS) technology as well. More specifically, it is pertinent to MOS capacitors used to internally compensate op amps. First, a review of semiconductor theory is presented followed by a discussion of damage mechanisms to MOS capacitors and a brief look at operational amplifier fundamentals. MOS capacitors, constructed by previous research efforts using the MOSIS technique, were selected as the internally compensating elements for simple low pass filters. Using the Naval Postgraduate School linear accelerator, these capacitors were irradiated with pulsed electrons possessing energies of up to 26 MeV for varying times. In-situ measurements were taken to immediately determine the capacitance value via the measured filter break frequency as a function of fluence. Separate irradiation runs were performed on three MOSIS capacitors and were terminated upon filter failure. This research concludes with a hypothesis of the filter fallure mechanism and suggested areas for expansion of continuing research efforts. This is believed to be the first time such an experiment has been performed.